I know it depends on angle, and shadow and such, but on a relatively level ground under California sun in September, how many amp do you see on the OEM Specialty Concept controller? I don't recall it ever was more than an amp. I wonder if I need to trouble shoot, or it is expected. I cleaned the panel recently.

You don't have your model year in your signature, so I'll pick a 1997, which is 20 years old. Although industry wisdom used to say a panel lost 1% efficiency a year, real life says more like 0.5%. So down by 10% = should put out max 3.1A by now.

Loss from not facing the sun could remove up to another 20%, so expect a little over 2.5A.

I know it depends on angle, and shadow and such, but on a relatively level ground under California sun in September, how many amp do you see on the OEM Specialty Concept controller? I don't recall it ever was more than an amp. I wonder if I need to trouble shoot, or it is expected. I cleaned the panel recently.

The controller limits the amps to what is actually needed for charging and 12V appliances. Try turning on some lights and the fantastic fan and see if the amps go up.

The OEM panels are pretty bullet-proof, but the Specialty Concept controller is not very efficient. I replaced mine with a Coleman PWM 3-stage controller, and it does a much better job using the panels and keeping the batteries maintained. I have two of the Siemens panels plus a flat 50-watt panel on top of the air conditioner.

It is out in the sunny spot, with no shadow. I'm going to try out Clay's suggestion. Maybe it was trickle-charging with only milliamp of current.

My next project is to upgrade the solar charger. Thinking about getting a MPPT, but with the usage that I am getting, I feel that it is a waste. I do have a few more modern 30A PWM chargers laying around in the garage, but they do not have the right type of mount to go in the spot where the current charger is.

1) Clay is correct in that you will only take in what you "need." Actually, the controller won't be limiting it in your case, but it's just that solar has to be "sucked" in. Meaning, if you batteries need 3 amps, your loads are 6 amps, and you have a 15 amp controller (and the panels to power it), you'll still only be taking in 9 amps at that moment. I use my Fantastic Fan as a quick ~3amp load, and any non-LED lights are good too.

2) That said, the Chinook system - while pretty darned cool for its day - has some big limitations.

a) It was only ever sized for "maintenance charging" (i.e. getting some amps into your battery while stored). With LED bulbs you can *slightly* use it for boondocking, but only slightly.

b) The Siemens panel is rather low voltage for modern day (it's 15.x volts; modern day "12 volt" panels range from around 17.5 volts to 19 volts or so). Why does that matter? A couple of reasons. One is that the whole process is lossy. The smaller the wires and the longer the wire run, the more lossy. The Chinook system has LONG, SMALL wires. So you have voltage drop. You essentially need "head pressure" to put power into the batteries. When you start out with only 15.x volts, lose a bunch of it along the way, and then say your batteries are in absorb (over 85% charged, presuming lead-acid batteries) and want 14.4 volts? You may not be able to give them that much, even in full sun, no other loads.

So, if you are looking for an automatic trickle charge when the Chinook is parked, then it's fine. If you are looking for "solar power" while you are camping? It's pretty marginal. If you wanted to change that, you could take some or all of these steps:

1) Get more/larger/higher voltage panels (meaning, not 15 volts, but more like 17-18).

2) Run larger wire/shorter run.

3) Put the controller closer to the batteries (especially if running panels in series and/or MPPT). The closer the better.

There are more details and potential tweaks, but those are the biggies, IMO.

And you don't need a monster system. I have 200 watts of ground panels and a small compressor refrigerator (DC) and I've been fine 95% of the time for 2-1/2 years of nearly constant boondocking. For those few times I'm not fine, I'll (finally!) get around to putting the pair of panels I have earmarked for the roof.

BTW, my oft-mentioned buddy just got a new RV. So, yep, time to re-do the electrical! We just finished round one yesterday, and he's sporting 200 watts of ground panels and an MPPT controller. This shows what the panels are putting in vs. the controller putting out (to the batteries). MPPT is definitely worth it, IMO, especially if you don't have a field in which to put more and more panels (i.e. limited roof space). Also, it allows for running panels in series (or series/parallel), which is a huge help if you want to use ground panels (you can have long, thinner wire leading to them), and can be a plus on the roof too (although not as clear a choice; with ground panels, it's all positive; with roof panels, there are arguments for parallel or series).

So if you wanted to do the minimum? Get another matching siemens panel (or another panel with matching amperage), and put it in series with the original. Then the skinny wire won't be as bad. Put something like a Morningstar Sunsaver 15 MPPT or Blue Sky 1512ix (or whatever letters they have on it now) close to the batteries, with larger cable between it and the batteries. (Or start over with "modern" 100 watt panels, but just saying what I would do if I really wanted to keep the original Siemens.)

Or if maintenance charging is all you need, then the original system will do some of that, as long as the batteries aren't too low when you start out (not sure how the original Siemens panels/wiring/controller would do at absorption voltages).

Thank you for the info, Blue. Very helpful. I think I probably will just want to make sure the current system is working properly, then when I have free time, I will look into MPPT controller. Right now, I just don't want the coach batteries to get damaged due to over-/under-charging. Clay suggested a controller, and I will try to learn more about it.

At 6pm, the sun was still out just not directly overhead, no shadow on the panel. I check the voltage, it says 12.7v. The current was 00.1A. I turn on the fans (bathroom and aisle), as well as some of the lights (none were upgraded to LED yet), and after a few minutes, the voltage dropped very slightly, but the current was still 00.1A. Should I hook my ammeter up to the controller's back and/or solar panel to confirm the reading?

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